Subcutaneous vs intramuscular testosterone injection

The clearest signal in the head-to-head data is that the two routes land in a similar place. In a study of 234 hypogonadal men, one group on intramuscular testosterone cypionate and one on a subcutaneous testosterone enanthate autoinjector (both 100 mg weekly) each raised trough total testosterone significantly, and after adjusting for other factors the route itself was not associated with the total testosterone reached. A separate prospective study in transgender adolescents found trough testosterone comparable between the subcutaneous and intramuscular groups by six months, with similar clinical and biochemical effects.

Subcutaneous dosing also tends to keep levels flat between shots. In a pharmacokinetic study of people on weekly subcutaneous testosterone, mean total and free testosterone stayed well within the normal range across the whole dosing interval. The practical read is that the subcutaneous route is a real alternative that reaches the target, not a compromise on levels.

Beyond the levels, the appeal of subcutaneous injection is mostly about the injection itself: a shorter, smaller needle into the fat layer rather than deep into muscle, which many people find easier to self-administer. In the adolescent study, most subjects were self-injecting within three months. Preference is not one-sided, though - in that same study, subjects voiced a preference for both routes, and both were judged safe and effective. Which one suits a given person is a clinical decision, and this page does not make it.

Testosterone raises hematocrit; that much is settled (see the high-hematocrit reference). Whether the injection route changes how much it rises is not. On one side, the 234-man study found the subcutaneous route was independently associated with lower post-therapy hematocrit than intramuscular cypionate, which fits the theory that a lower peak-to- trough ratio produces a milder red-cell response.

On the other side, a 2024 review notes that head-to-head trials on this exact question are largely lacking, and that a network meta-analysis concluded all testosterone formulations raise hematocrit - with intramuscular enanthate/cypionate the most potent compared with transdermal patches, but the effect present across the board. So the honest summary is that the route may matter for hematocrit and some data suggests it does, but the evidence is thin and mixed enough that no one route can be called the erythrocytosis-safe one. We report the conflict rather than resolve it.

There is one FDA-approved subcutaneous testosterone product, XYOSTED (testosterone enanthate). Its label is a useful, concrete reference point for the route. It is given in the abdominal region only, with the label explicitly telling users to avoid intramuscular and intravascular injection. The starting dose is 75 mg once weekly, and trough total testosterone is checked seven days after a dose. In trials, 90% of men (135 of 150) reached an average concentration inside the normal range by Week 12.

On the hematocrit point above, the label does not treat the subcutaneous route as exempt: it directs evaluating hematocrit about every three months and stopping the drug if hematocrit becomes elevated - the same vigilance applied to any testosterone route.

The Endocrine Society clinical practice guideline frames testosterone replacement around reaching the mid-normal range and monitoring hematocrit, and it lists both intramuscular and subcutaneous injection among the available preparations. It does not declare one route superior. That neutrality is consistent with the evidence here: the levels are comparable, the subcutaneous shot is often easier, and the hematocrit-by-route question stays open. Anything about your own dose or route is a conversation for you and your prescriber - the sections above only log what the sources report.